1. Field of the Invention
This invention relates to a system for making electrical contacts available for an electrochemical polishing operation and, more particularly, to providing contacts arranged on a metal strip for provision to the electro-chemical polishing operation.
2. Description of Background
The use of very fine wires as electrical contacts in positional encoders, in slip-ring assemblies, precision potentiometers, sensors, or the like is known. It is further known that the contact end of each of such fine wires must be polished in order to eliminate any burrs or the like that would decrease the contact area between the contact and its contact surface. Such polishing is also required to cut down on the extent that the wire contact abrades the mating electrical contact surface.
One known approach to smoothing or rounding off of the ends of very small diameter wires or springs is disclosed in U.S. Pat. No. 5,189,278 in which a laser beam is used to irradiate the ends of the wire or spring so that the end is melted somewhat. While some advantageous results are had by this approach, the melting of the end of the wire or spring results in a loss of temper of the metal. Moreover, in order to properly irradiate the end of the wire with the laser beam, the wire must be separated by more than a nominal distance from its adjacent wire or spring, so that embodiments in which multiple springs are arranged side-by-side in contact with each other are not available for use with the laser technique described in the above-mentioned U.S. patent.
Another approach to smoothing metal objects is known as electro-chemical smoothing, whereby a surface of a conductive metal part can have the burrs removed. One technique for performing such a function is described in U.S. Pat. No. 4,752,376. Nevertheless, application of the electro-chemical smoothing process to extremely fine wire contacts poses difficulties in the implementation because the fine wire assemblies are difficult to handle.
Accordingly, it is an object of the present invention to provide a system whereby the end surfaces of very fine gauge wires forming metal spring contacts can be polished and that can eliminate the above-noted defects inherent in the prior art.
Another object of the present invention is to provide a system for continuous polishing or smoothing of the tips of fine gauge wire electrical contacts mounted on a thin, flexible metal strip for ease of transport and polishing in an electro-chemical polishing operation.
In accordance with an aspect of the present invention, small diameter wire contacts are fixed onto a flexible metal strip that is wound on a spool and transported to an appropriate location whereat an electro-chemical polishing operation is performed on the tips of the wire contacts in a continuous fashion. The contacts and wire strip are then wound up again on a spool for transport to the ultimate manufacturing location. A metering operation takes place to control the supply and take-up spools under control of a microprocessor that permits various inputs by the user of the system.
In accordance with another aspect of the present invention, small diameter wire contacts are fixed onto a flexible metal strip and transported to an appropriate location whereat short lengths of the flexible metal strip are fed to where an electro-chemical polishing operation is performed. The strips with the polished wire contacts are then collected for subsequent use.
The above and other objects, features, advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof to be read in conjunction with the accompanying drawings.